Effects Of Four Materials On The Utillzation Of Dietary Plant Proteins Of Litopenaeus Vannamei

This study was conducted to study the effects of partial replacement of fish meal(FM) by soybean meal(SBM) and peanut meal(PNM) combined with four dietary materials(coated lysine and methionine, compound Bacillus, phytase and nucleotide mixture) on the growth performance, body composition, serum biochemical indices, antioxidant function and immune, digestive enzyme activities, histological structure of digestive organs and apparent digestibility of different diet nutrient in Litopenaeus vannamei. The contents and results are as follows:1. The effects of four dietary materials on growth performance, body composition,serum biochemical antioxidant function and immune of Litopenaeus vannamei fed diets with partial replacement of fish meal by SBM and PNM.The experiment was conducted to study the effects of four dietary materials on growth and biochemical indices in Litopenaeus vannamei fed diets with partial replacement of FM by SBM and PNM, with an initial mean weight of 1.70 g. The prawns in control group were fed the basal diet(G0) containing 23% FM, 22% SBM and 18% PNM,while those in the other four treatment groups were fed the basal diet added with 212 mg/kg coated lysine and 84 mg/kg methionine, 1010 CFU/kg compound Bacillus, 1000 U/kg phytase and 620 mg/kg nucleotide mixture respecitvely, named as G1,G2,G3 and G4. After 8 weeks of feeding, the results showed:(1) Final body weight(FBW), weight gain rate(WGR), specific growth rate(SGR) and protein efficiency ratio(PER) were significantly higher and feed coefficient(FC) were significantly lower in the four treatment groups than those in G0(P<0.05). Protein deposition ratio(PDR) of G2 and G3 were significantly higher(P<0.05). There was no significant difference in condition factor(CF), hepatopancreas index(HI) and survival rate(SR) in the four treatment groups.(2) Compared with G0, the body crude lipid content in G3 and G4 significantly increased but the crude ash content in G2 and G3 was significantly lower(P<0.05). The moisture and crude protein(CP) content in the four treatment groups were not significantly different from those in G0(P>0.05).(3) The total protein, cholesterol and triglyceride content of serum in the four treatment groups were significantly higher than those in G0. The serum albumin content in G1 and G2 and serum glucose content in G1 and G3 were significantly higher than those in G0. Glutamic oxalacetic transaminase(GOT) and glutamic pyruvic transaminase(GPT) in the four treatment groups were not significantly different from those in G0(P>0.05).(4) The POD,T-AOC, PO and LZM activities in G2 and the T-AOC activities in G4 were significantly higher than those in G0. No significant difference was found in SOD and MDA activities among the five groups. The results indicated that dietary coated methionine and lysine, compound bacillus, phytase, nucleotide mixture could improve growth performance and non-specific immunity of Litopenaeus vannamei and the utization of SBM and PNM. Compound bacillus is better than the other three dietary materials.2. The effects of four dietary materials on the digestive enzyme activities and the intestine histological structure of Litopenaeus vannamei fed diets with partial replacement of fish meal by SBM and PNM.The liver, stomach and intestine were taken from 3 piece of Litopenaeus vannamei at the end of the feeding experiment, added 9 times of normal saline and kept at-80℃ for analysing protease, lipase and amylase activities of liver, stomach and fore intestine. The same part of fore intestine was taken for paraffin slice. The results showed that:(1) Compared with G0, stomach protease activity had a tendency to rise in the four treatment groups; the intestinal protease activity in G3 is significantly higher than G0(P<0.05), but there was no significant difference in G1, G2 and G4(P>0.05); The hepatopancreas protease activity in G2 was significantly higher than G0 and G1(P< 0.05); The stomach amylase activity in G2 and G3 was significantly higher than G0 and G1; The hepatopancreas amylase in G2 was the highest, and was significantly higher than G0(P<0.05); The intestinal amylase activity had a tendency to rise in the four treatment groups; Except for G1, stomach lipase activities in the other groups had a tendency to rise;The highest intestinal lipase activity in G2 was significantly higher than G0 and G1(P<0.05);The four Treatment groups of hepatopancreas lipase activity had a tendency to rise, and G2 was the highest, followed by the G3.(2) The Jejunum wall thickness in G2, G3, and G4 was significantly higher(P<0.05) than G0, with G2 the highest, but there was no significant difference between G0 and G1.(P>0.05); Intestinal villus height in G2, G3, and G4 was significantly higher than the other groups, and G2 is the highest, followed by G4 and G3(P<0.05). The results showed that the groups with additives could not only enhance the protease activities of hepatopancreas and intestine and the stomach amylase, but also improve the muscle layer of intestine, the height and density of microvillus of intestine and increase the tight between the inherent layer and epithelial cells.3. The effects of four dietary materials on the apparent digestibity of diet nutrients of Litopenaeus vannamei fed diets with partial replacement of fish meal by SBM and PNM. The apparent digestibility experiment was conducted after the feeding experiment. The diets contained 0.04% Y2O3. Fresh and complete feces were collected a week later for analysing the nutritional values. The results showed that AD of dry matter and crude lipid in the four treatment groups were significantly higher than those in G0. Compared with G0, AD of crude protein and phosphorus were significantly higher in G2 and G3, and AD of energy were not significantly different in the four treatment groups. All the AD of amino acids(except for Gly and Cys in G1) were more than 85% in all the groups. Compared with G0, the amino acids in G1, except for the Phe, Pet, Thr, Pro and Cys, were not significantly different(P >0.05), and AD of all amino acids in G2, the amino acids in G3(except for Pro and Tyr) and G4(except for Lys, Arg, Ser and Tyr) significantly increased(P < 0.05). The results indicated that dietary coated methionine and lysine, compound bacillus, phytase, nucleotide mixture could improve apparent digestibility(AD) of diet nutrients for Litopenaeus vannamei, and especially the effects of compound bacillu and phytase were better than the other two materials.